A typical fixed network automatic meter reading system comprises some utility meter data origination sites, repeaters, gateways, and a backhaul network. The utility meter data origination points include radio frequency transmitters or transceivers located at a utility meter, which is contemplated as a water meter or a gas meter. Typically, these utility meters are not connected to a source of AC power and they are operated on battery power, which distinguishes them from electric meters which have a ready source of electrical power. The transmitters or transceivers communicate with receivers via a wireless radio frequency communication link. If these receivers communicate with a large number of utility meter data origination sites (hereafter sometimes referred to simply as “sites”) either directly or through relay devices known as repeaters, and also interface to a backhaul network, they are known as gateways. Gateways collect the data from a plurality of utility meter data origination sites and pass the information through a wired or wireless network (local or wide area network), sometimes called a “backhaul network,” to a central data collection system, where the data is processed for billing purposes. This backhaul network may include various public or private systems such as the WIFI (a wireless LAN), GPRS (a second generation cellular network), POE (Power over Internet), or CDMA (code division multiple access) or others known in the art.
These systems. both mobile and fixed, were known in the art as AMR systems or “Automatic Meter Reading Systems.” More recently, the term “AMI” or “Advanced Metering Infrastructure” has been used to describe fixed network systems with some two-way communication abilities.
Cerny et al., U.S. Pat. No. 5,298,894, discloses an early example of a mobile automatic meter reading (AMR) system in which a utility meter transmitter transmits radio frequency (RF) metering data from subsurface utility meter enclosures to an RF collection unit.
Gastouniotis et al., U.S. Pat. No. 4,940,976, discloses an early example of a fixed network for transmitting data from a plurality of remote metering sites to a data center through a plurality of fixed receiving stations. In fixed receiver network systems today, the receiver units can be mounted on utility poles, or on water storage tank towers, or inside of electric meters or in utility pedestals. As opposed to mobile systems, it is not necessary to provide people and equipment to travel through the areas where readings are to be collected.
There is a problem in installing and operating fixed network systems in that various features of the topography, such as trees, buildings, uneven terrain, and structures, particularly metal structures, may attenuate or block signals from different sites where meters and transmitters are located.
AMR and AMI systems must communicate over a limited number of radio frequency channels. Integrated circuits supporting these communications are designed to operate over this limited number of radio frequency channels. Relatively lower frequencies are preferred for transmitting through obstructions. The number of channels licensed by the Federal Communications Commission is a limitation, and the bandwidth of operation on these channels is another limitation.
There is also the problem that remote site transmitters operate on battery power, and therefore, simply increasing power levels for transmitter operation is not an overall system solution if it shortens battery life. The system must be adaptable to allow a large number of remote sites to communicate through gateways to a network data reader at a data collection center.